Coronal holes

A recurrent trans equatorial coronal hole (CH240) was in an
Earth facing position on September 20-21. A recurrent coronal hole (CH241) has
rotated into view at the east limb and will likely be in an Earth facing
position on September 26-27.

Processed SOHO/EIT 284 image at 19:06 UTC on September 21. The
darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is
expected to be mostly quiet on September 22 becoming
unsettled to minor storm on September 23-24 due to a high speed stream from
CH240. Quiet to unsettled is likely on September 25 with mostly quiet conditions
on September 26-28.

Coronal holes (1)

Coronal mass ejections (2)

M and X class flares (3)

1) Effects from a coronal hole could reach Earth
within the next 5 days. When the high speed stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.

Propagation

Long distance low and medium
frequency (below 2 MHz) propagation
along east-west paths over high and upper middle latitudes is fair. Strong
signals were noted from stations like 850 WEEI, 1130 WBBR and 1510 WWZN. A few
stations from Cuba, Venezuela and Colombia had good signals as well. Propagation on long distance northeast-southwest paths
is poor.

Data for all numbered solar regions according to the Solar Region
Summary provided by NOAA/SEC. Comments are my own, as is the
STAR spot count (spots observed at or inside a few hours before
midnight) and data for regions not numbered by SEC or where SEC has observed no spots.
SEC active region numbers in the table below and in the active region
map above are the historic SEC/USAF numbers.

Active region

Date numbered

SEC
spot
count

STAR
spot
count

Location at midnight

Area

Classification

Comment

10910

2006.09.18

1

3

S09E10

0010

HSX

classification was CSO at midnight, area 0030beta-gamma

Total spot count:

1

3

SSN:

11

13

Monthly solar cycle data

Month

Average solar
flux at Earth

International sunspot number

Smoothed sunspot number

2000.04

184.2

125.5

120.8
cycle 23 sunspot max.

2000.07

202.3

170.1

119.8

2001.12

235.1

132.2

114.6 (-0.9)

2005.07

96.4

40.1

29.1 (+0.3)

2005.08

90.5

36.4

27.4 (-1.7)

2005.09

91.1

21.9

25.8 (-1.6)

2005.10

77.0

8.5

25.5 (-0.3)

2005.11

86.3

18.0

24.9 (-0.6)

2005.12

90.7

41.2

23.0 (-1.9)

2006.01

83.4

15.4

20.8 (-2.2)

2006.02

76.5

4.7

18.6 (-2.2)

2006.03

75.4

10.8

(17.1 predicted, -1.5)

2006.04

89.0

30.2

(16.4 predicted, -0.7)

2006.05

80.9

22.2

(15.9 predicted, -0.5)

2006.06

76.5

13.9

(14.1 predicted, -1.8)

2006.07

75.7

12.2

(12.4 predicted, -1.7)

2006.08

79.0

12.9

(11.9 predicted, -0.5)

2006.09

80.0 (1)

18.1 (2)

(11.9 predicted, -0.0)

1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC)
sunspot number. The official international sunspot number is typically
30-50% lower.

This report has been prepared by Jan
Alvestad. It is based partly on my own observations and analysis, and
partly on data from some of these solar data sources.
All time references are to the UTC day. Comments and suggestions are always welcome.